Garland GPD Series, Installation And Operation Manual

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Document #: G_GO_OM_PYRODECK_4606131 – 12/20 Page 9
Gas Pressure Adjustments
All GPD Series ovens are equipped with fixed orifices and
cannot be adjusted for gas flow: If necessary, pressure
adjustments can be made at the pressure regulator (located
on the combination gas valve).
A pressure tap is supplied with the unit and it is installed
on the manifold, downstream of the main valve. The gas
pressure must be checked when the unit is installed, to
ensure that the unit gas pressure is the same as specified on
the rating plate.
Flame & Air Mixture Adjustment
After the pilot burner is ignited, when heat is desired, turn
gas cock dial to “ON” position and set the thermostat dial
to the desired temperature. The oven burner flame should
always have a blue appearance. This indicates a good mixture
of air and gas. When using LP gas the flame will have a blue
yellow appearance. Follow steps 1 thru 4 to adjust the flame
for good quality.
1. Loosen the small knurled locking disk.
2. Turn the large adjusting disk towards the air mixture
throat to reduce the opening. This restricts the amount of
air, causing the flame to turn yellow.
3. Turn the adjusting disk gradually out, away from the air
mixer throat, allowing more air into the air mixer until the
yellow disappears and a sharp blue flame appears.
4. When the flame turns blue and spreads out, turn the
locking disk tight against the adjusting disk. There may
be intermittent yellow-orange flame noticed. This is
caused by dust particles burning in the Flame. Should the
burners fail to light, check to see if there is a problem with
any or all of the following.
ADJUSTMENTS
A. The gas supply: If there are other gas appliances on the
same supply line, shut them off temporarily and see if
the flame comes back on, or if it fluctuates as other gas
appliances are turned on and off. If so, it would indicate
overloading of the gas supply or a faulty gas pressure
regulator. You should contact a qualified service agency
or the local gas company to check the gas supply.
B. Dirty burner orifice or ports: With the oven cold, use a
thin wire to check that the spud orifice (nozzle) is clear. If
necessary, loosen and remove the spud. Be careful when
cleaning not to enlarge the hole. Then, using a wire or
thin nail, clear the burner ports of carbon deposits or
other restrictions.
Periodically, after breaking the ovens in, check the burner
flame and readjust the air mixture if needed. Black soot on
the oven doors or in the burner compartment may indicate
that not enough air is mixing with the gas. If this is the case,
back off the air adjustment disk until the proper flame and
color is set.
By-Pass Flame Adjustment
The by-pass in the thermostat is a small gas supply through
the control that is independent of the dial setting. It is
controlled strictly by the Adjusting Screw. This small gas
supply maintains a minimum flame or the burner(s), helping
to maintain the heat in the oven and assisting in recovery.
This adjustment is best done when the oven is being heated
for the day’s business. To adjust the by-pass flame follow
steps 1 thru 4.
1. Turn the oven on and set the thermostat to the desired
temperature.
2. Allow the oven to pre-heat until the burner flame begins
to throttle down.
3. At this point, turn the thermostat dial all the way down.
This ensures that the thermostat is in the by-pass mode.
There should now be a small steady flame remaining
across the burner without flickering or going out.
NOTE: It may be necessary to turn the thermostat back up to
relight the burner(s) if there is not flame present.
4. Using a small screwdriver, reach through the access hold
on the control panel to the left of the thermostat knob.
Turn the by-pass adjustment screw to raise or lower the
by-pass flame as required. Counter-clockwise raises the
flame, clockwise lowers the flame. Take care not to turn
the screw out too far as that will allow gas to leak around
the adjustment screw.
IMPORTANT:
All gas burners and pilots need sufficient
air to operate and large objects should not
be placed in front of this oven, which would
obstruct the airflow through the front.
Objects should not be placed on main rear of
oven while in use.